ARAMID FIBRE-REINFORCED RUBBER

The traditional TPS for launcher fairings and re-entry capsules consists of an external ablative insulation, fixed or bonded onto a metallic primary structure. Ablative materials are based on thermosets (phenolic and epoxy resins) or elastomers (ethylene-propylene and silicone rubbers) usually filled and reinforced with cork, cotton, glass, silica, quartz, carbon, silicon carbide, nylon and aramid in the form of powders, fibres, fabrics and felt (Table 2). 

Most technical yams for reinforcement are based on continuous multifilament yams having linear densities typically in the 1100 dtex (1000 denier) region in singles or doubled configurations. The number of filaments per yam will vary between about 140 and 200 for melt-spun nylon 6.6 and polyester to >500 for high tenacity viscose and other wet-spun fibres, including the aramids. For instance, Kevlar 29, suitable for rubber reinforcement, is available as a 1670 dtex yam with 1000 filaments. "... 

Short fibres of glass, rayon, aramid, asbestos and cellulose as reinforcing fillers, have been broadly used in rubber industries due to their high modulus, high strength and low creep. In recent years especially, natural fibres such as jute fibre, cellulose fibre, " coir fibre," " sisal fibre," " etc. have been also widely used in NR composites because they are enviromnental friendly, cheap, abundant and renewable. However, natural fibres also have some disadvantages such as moisture absorption, quality variations, low thermal stability and poor compatibility with the hydrophobic polymer matrix. 

Ethylene-carbon monoxide polymers offer superior performance as high-strength fibres for aramide tyre cord, but at a significantly lower cost. Their structure is more compatible with rubber than steel, polyester, or PA tyre reinforcements. 

---